Field
This disclosure relates to data communications networks and more particularly to network switches with hierarchical security.
Description of the Related Art
Communications networks commonly contain a mesh of transmission paths which intersect at hubs or nodes. The transmission paths may be wired, wireless, or optical. Optical fiber links are commonly used to provide high bandwidth transmission paths between nodes. Such optical fiber links form the backbone of wide area networks such as the Internet. Optical fiber links are also applied in high bandwidth local area networks which may be used, for example, to connect server racks in large data centers or to connect processors in high performance computers.
At least some of the nodes in a communications network may include respective switches. In this patent, the term “switch” means a device that receives data or information arriving at a node via two or more incoming transmission paths and selectively forwards that data along two or more outgoing transmission paths. This definition of “switch” encompasses devices that may commonly be called switches, routers, and bridges. Switches used in communications networks include packet switches and circuit switches. Packet switches route data packets based on addressing information contained within each packet. Circuit switches connected designated transmission paths without regard for, or knowledge of, the content of the data traveling along the communications paths. Circuit switches may be optical or electronic.
An optical circuit switch is a switching device that forms connections between pairs of optical fiber communications paths without converting the optical signal into electrical signals. A typical optical circuit switch may have a plurality of ports and be capable of selectively connecting any port to any other port in pairs. Since an optical circuit switch does not convert information flowing over the optical fiber communication paths to electrical signals, the bandwidth of an optical circuit switch is essentially the same as the bandwidth of the optical communications paths. Further, since an optical circuit switch does not convert information into electrical signals, the power consumption of an optical circuit switch may be substantially lower than a comparable electronic circuit switch.
Whether a network uses packet switches, optical circuit switches, electronic circuit switches, or combinations thereof, it is paramount that data not be inadvertently or maliciously transmitted to an incorrect destination. To this end, security provisions may be incorporated into network switches.
Throughout this description, elements appearing in figures are assigned three-digit reference designators, where the most significant digit is the figure number where the element is introduced and the two least significant digits are specific to the element. An element that is not described in conjunction with a figure may be presumed to have the same characteristics and function as a previously-described element having the same reference designator.